1) Field of the Invention
The present invention relates to a pick-up feeding device for feeding an optical pick-up relative to an optical disc.
2) Description of the Prior Art
In general, an optical disc is used as a recording medium onto which information can be recorded or from which information can be reproduced, the information being contained on spiral or concentric tracks of the disc. The information recorded on the disc is reproduced by a disc loading device for loading/unloading the optical disc and an optical pick-up which projects laser beams on recording pits of the disc.
A conventional apparatus, as shown in FIGS. 1 and 2, includes a rotatable turntable 12 which is located on a deck base 10. Non-magnetized portions of the optical disc make contact with the turntable 12. The turntable 12 is engaged with a rotary shaft of a spindle motor 14 to be driven thereby. On one side of the spindle motor 14 are installed an optical pick-up 16 for recording and reproducing information on and from the disc, and a pick-up feeding device for feeding the optical pick-up in a radial direction of the optical disc.
The conventional pick-up feeding device includes a motor 20 which is mounted on the rear side of the deck base 10, a drive gear 22 which is engaged with a rotary shaft of the motor 20, a driven gear 24 which is rotated by the drive gear 22 and, a lead screw 26 which is rotatably mounted to the driven gear 24. A guide shaft 28, arranged parallel to the lead screw 26, guides a pick-up base 18 of the optical pick-up 16 which is fixed to the lead screw 26. The guide shaft 28 is mounted in supports 30 molded integrally with the base 10.
According to the conventional pick-up feeding device, a current is applied to the motor 20 when it is desired to record and reproduce information on and from an optical disc in contact with the upper surface of the turntable 12. The drive gear 22, the driven gear 24, and the lead screw 26 mounted to the driven gear 24 are all rotated, so that the pick-up base 18 is fed in a radial direction of the optical disc and guided by the guide shaft 28, to record and reproduce information on and from the optical disc.
Both ends of the guide shaft 28 are fixed to respective U-shaped fixing portions which are fixed to the deck base 10. An unthreaded end portion of the lead screw 26 is connected to the driven gear 24, and the other end thereof is rotatably mounted in a fixing portion 32 which is molded integrally with the deck base 10. The lead screw 26 and the guide shaft 28 are disposed in parallel to the feeding direction of the optical pick-up 16, i.e., the horizontal direction X.
However, in case the fixing portion 32 formed on the deck base 10 is twisted or shrunk during cooling processes of the fixing portion 32 after molding, the lead screw 26 becomes out of parallel to the horizontal X axis and the guide shaft 28 and becomes tilted in a direction (Z-direction). In the conventional pick-up feeding device, there is no separate means for regulating the parallel relationship of the lead screw 26 with the X axis, so the optical pick-up may not be smoothly fed due to the load exerted on the lead screw 26 by the pick-up base, and therefore the pick-up base 18 cannot be accurately halted at a desired position.